Cathode-ray tube manufacturing apparatus



Aug. 12, 1958 J. J. o'cAL-LAGH 2,846g973 cA'rHoDE-RAY TUBE MANUFACTURINGAPPARATUS Aug. 12, 1958 .1.J. o'cALLAGHAN 2,846,973

cATHoUE-RAY TUBE MANUFACTURING APPARATUS Filed July 2e, 1957 2Sheets-Sheet 2 5* 8 bwl l l United States PatentfOffice 2,846,973Patented Aug. 12, 1958 CATHODE-RAY TUBE MANUFACTURING APPARATUS JeromeJ. OCallaghan, Skokie, Ill., assigner to The Rauland Corporation, acorporation of Illinois Application July 26, 1957, Serial No. 674,332

2 Claims. (Cl. 118-317) This invention relates in general to cathode-raytubes and in particular to apparatus for applying an organic film to theexposed luminescent screened faceplate of cathode-ray tubes.

Preparatory to the aluminizing process in the manufacture of aluminizedcathode-ray tubes, a lacquer film is applied to the prepared luminescentscreen affixed to the inside surface of the envelope faceplate. Thislacquer film serves as a foundation upon which aluminum vapor can bedeposited and must be so applied as to form a uniform and taut base ifthe subsequently deposited alu- 'minum is to provide a mirror-likebacking for the luminescent screen.

A conventional lacquer filming method is based on a flotation processwhich utilizes a water column upon which lacquer is deposited.Subsequent decantation of the Water permits the lacquer film to adhereto the luminescent screen. An obvious shortcoming of this process is thetime consuming element. Another known lacquer filming process involvesthe use of stationary spraying apparatus in conjunction with a mechanismwhich rotates the cathode-ray tube envelope while the lacquer is sprayedon to its luminescent surface. In practicing this method, rotating theenvelope is necessary in order to distribute the lacquer uniformly overthe luminescent screen. This spinning requirement raises difficulties inthe adaptation of such a method to automation activities since theindividual cathode-ray tube envelopes must be positioned upon thespinning mechanism or otherwise disassociated from the conveyor whichtransports the envelopes during the manufacturing process prior to thelacquer spraying operation.

The copending application of Nathan D. Levin forv Cathode-Ray TubeManufacturing Method and Apparatus, filed concurrently herewith andassigned to the present assignee, discloses and claims a spray filmingmethod and apparatus in which the envelope is held stationary and arotating lacquer spray is employed. The present invention is directed toan improvement of the basic apparatus for performing the methoddescribed and claimed in the Levin application.

In accordance with the invention, therefore, it is a primary object toprovide a novel apparatus for applying an organic film to theluminescent screened surface of a cathode-ray tube envelope.

It is also an object of this invention to provide novel lacquer filmingapparatus which renders unnecessary any manipulation of the cathode-raytube envelope during the filming operation.

It is a corollary object of this invention to provide lacquer filmingapparatus amenable to automation.

Another important factor to be considered in spray filming techniquesconcerns the lacquer material itself, which because of its inherentvolatility and tackiness poses handling and sealing difiiculties. It isthus apparent that in addition to managing the envelope, dueconsideration must be accorded the materials utilized as well as thestorage and dispensing thereof.

Accordingly, it is a further object of this invention to provide sprayfilming apparatus which obviates thereyquirement of complex lacquerseals.

In accordance with the invention, apparatus for applying an organic filmto the luminescent screened surface of acathode-ray tube envelopeincludes means for supporting the envelope in a fixed position with itsaxis vertically oriented and with the faceplate of the envelopeuppermost. A coaxial conveyor comprises film solution conveying meansand includes a stationary inner conduit coupled to a liquid supply oflacquer material, and a rotatable outer conduit coaxial with said innerconduit. The outer conduit is coupled to a supply of compressed gas. Thecoaxial conveyor extends vertically into the cathode-ray tube envelopeand includes a nozzle, fixed to the upper extremity of the outerconduit, which communicates with both conduits. Further, means areprovided for rotating the outer conduit with respect to` the innerconduit to produce a rotating spray of atomized lacquermaterial Withinthe envelope and directed toward the luminescent screen.

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The organizationand manner of operation of the invention, together with further objectsand advantages thereof, may best be understood by reference to thefollowing description taken in connection with the accompanyingdrawings, in the several figures of which like reference numeralsidentify like elements and in which:

Figure l is a side elevation View, partly in section, of a film sprayingapparatus embodying the invention;

Figure 2 is a sectional view of the nozzle arrangement utilized in thefilm spraying apparatus;

Figure 2a is a cross-sectional view taken along the line Za-Za of Figure2; and

Figure 3 is a top View of the cathode-ray tube enve- 4 lope depicted inFigure l.

The film spraying apparatus'as shown in Figure 1 includes a table 10which supports a drive motor (not shown) that is coupled to a shaft 13which is journalled within a bearing 14 and fixed to a driver pulley 15.Pulley 15 is coupled to a centrally located drive wheel 91 through adrive belt 17. A conventional lock screw 92 secures drive wheel 91 tothe outer rotatable conduit 93 of a coaxial conveyor device 94 which isterminated at its upper extremity by a nozzle 55 which comprises anatomizer and is specifically described below in relation to Figure 2.Coaxial conveyor 94 further comprises a stationary inner conduit and adisplaceable metering pin 96.

A pair of uprights 61, fastened to surface 150 of table 10, mount anapertured guide plate 62 which in turn carries the demountable uprights63. Uprights 63 are terminated by a ring 64 which supports andvertically orients a cathode-ray tube envelope 65 having a preparedluminescent screened surface 66. Vertically positionable upon supports61 is a drain pan 67, which includes a deflector pad 68, centrallydisposed about coaxial conveyor 94. Pan 67 is positionably secured byconventional fasteners 69. A water supply inlet (source not shown) isterminated by a control valve 70 and provides a constant wash for pan67. An outlet tubing 71 is connected to drain pan 67 Rotatable conduit93 of coaxial conveyor 94 communicates with an air pressure chamber 97which is secured to surface of table 10 whereas conduit 95 and pin 96are terminated by a lacquer well 98 in a manner to be more fullydescribed below. Conduit 93 is provided with an upper bearing supportshoulder 99 and a lower shoulder 100 for seating the bearings101,1102'respectively, which `bearings comprise rotatable inner races103 inti- 3 mately contacting conduit 93 and stationary outer races 104secured to chamber 97.

A hermetic rotatable air seal comprises a bellows 105, sealed toyconduit 93 -by a ring 106, and a rotatable lapped-'surface bearing 107depending therefrom and journalled upon a stationary lapped-surfacebearing insert 108 supported by a pedestal 109. In order to insure anadequate air seal, rotatable bearing surface 107 can comprise stainlesssteel whereas stationary bearing insert 108 is preferably of adissimilar material, e. g., a graphite material. Vents 110 communicatebetween enclosure 111 of chamber 97 and the space included betweenrotatable conduit 93 and stationary conduit 95. A source of pressurizedair is coupled through a control valve 112 to an inlet fitting 113 fixedto chamber 97. An electrically operated solenoid 114 is operablyassociated with valve 112.

Lacquer well 98 is hermetically sealed by the lacquer seal 115 to amounting plate 116 and secured thereto by the conventional screws 117.The mounting plate 116 and an air seal gasket 118 are hermeticallysealed to chamber 97 and fastened by bolts 119. The lower extremity ofpipe 95 is vented to well 98 and secured within the apertured shoulder120 of mounting plate 116. The terminus of metering pin 96 is fixed to adiaphragm 121 depending from well 93. An inlet 122 admits lacquer, whichcan comprise isobutyl methacrylate, under pressure to well 98. An arm123 pivotally mounted upon a pin 124 is in permanent contact withdiaphragm 121 and has a crank element 125 driveably engaged to thedisplaceable plunger 126 of an electrically operated solenoid 127. Arestoring spring (not shown), disposed within solenoid 127, engagesplunger 126 to bias arm 123 in a counter-clockwise direction whensolenoid 127 is denergized. A threaded bar 128 provided with a lock nut129 cooperates with a tab extension 130 of arm 123 to comprise a limitarrangement for metering pin 96.

Figure 2 comprises a sectional view of the upper extremity of conveyordevice 94 (including nozzle 55) which illustrates the structuralcooperation between device 94 and nozzle 55. Protruding from the innerperiphery of rotatable conduit 93 are shelves 131 which support arotatable bearing 132 of nylon, or other suitable material, providedwith longitudinal apertures 133 for communicating between an annularchamber 77 and conduit 93. Bearing 132 further affords a measure ofrigidity to coaxial conveyor 94.

An insert 78 has a threaded portion 79 at its lower extremity forattachment to a correspondingly threaded inner surface of stationaryconduit 95. Insert 78 maintains a conical portion 80 at its upperextremity and includes a tapered channel 81 for communicating at itsupper end with the central bore 82 in nozzle 55 and at its opposite endwith conduit 95. The base 83 of nozzle 55 is seated upon a gasket 84 andis demountably secured within the crown 85 which terminates outerrotatable conduit 93 by a collar 86. The conical portion 89 of insert 78 in conjunction with the inner surface -of nozzle base 83 defines apassage 87 between annular chamber 77 and bore 82. Preferably, nozzle 55is provided with an offset portion 88 incorporating an asymmetricaldischarge orifice which terminates bore 82 of nozzle 55, as describedand claimed in the copending application of Francis Kinsch forCathode-Ray Tube Filming Apparatus tiled concurrently herewith andassigned to the present assignee.

In operation the subject invention contemplates the application of alacquer film to the luminescent screened surface 65 of a cathode-raytube envelope 65, by directing a rotating spray of an air-lacquermixture thereupon. With reference to the above described apparatus, itis apparent that upon energization of a driving motor, rotational energyis translated through shaft 13 and driver pulley to propel drive wheel91 via belt 17. The driven arrangement comprises merely the outerconduit 93 of coaxial conveyor 94 which is secured to drive wheel 91. Inorder to obviate the requirement of periodically replenishing a lacquersupply the described apparatus provides for an external pressurizedlacquer Source coupled to well 98 which is coupled to the stationaryinner conduit in order to obviate the requirement of a rotating lacquerseal. An initiating procedure amenable to automation techniques may beutilized which employs a conventional timing mechanism (not shown) tofirst energize the driving motor to bring rotatable coudit 93 to apredetermined operating speed. Thereafter electrical energization ofsolenoid 114 opens valve 112 to admit pressurized air to chamber 97. Thepressurized air is introduced to rotating conduit 93 through vents 11i)and conveyed to nozzle 55. Actuation of a second solenoid 127 initiatesthe ow of pressurized lacquer from well 98 to nozzle 55. Specifically,energizing solenoid 127 displaces plunger 126 which drives crank elementso as to pivot arm 123 in a clockwise direction about pin 124. Thispivotal rotation of arm 123 permits metering pin 96 to withdraw fromtapered channel 81. The travel of arm 123 ceases when extension 130contacts bar 128 which, in comprising an adjustable limit arrangement,determines the iiow rate of lacquer through conduit 9S to channel 81.

With reference to Figure 2 (and Figure 2a), it is noted that uponadmission to conduit 93, pressurized air passes through apertures 133,annular chamber 77 and passage 87 to confront pressurized lacquer at theentrance to bore 82 in nozzle 55. The juncture of passage 87 and channel81 comprise, in effect, a volatilization chamber or atomizer whichproduces a turbulent mixture of air and lacquer for introduction to bore82. Offset 88 directs the aforesaid mixture obliquely with respect tothe axis of tube 65. An asymmetrical orifice terminates bore 82 andtransforms the air-lacquer mixture into the diverging mist 289, shown inelevation in Figure l and in plan in Figure 3. The configuration anddensity of mist 280 insures a uniform deposit of lacquer film on surface66 by directing a comparatively heavy stream of air-lacquer mistoutwardly towards the periphery of tube 65 while providing aprogressively decreasing mist density as the axis of tube 65 isapproached. Offset 88 further provides that the upward discharge of mist200 perceptibly overlaps the geometric center of the tube in order toobviate a blank or non-uniform film layer on that area. The deflectorpad 68 protects coaxial conveyor 94 and its associated apparatus bydiverting excess lacquer to the adjustable drain pan 67 which isprovided with a water circulatory system and continually drains to carryofi such excess.

Upon completion of the spraying operation, deenergization of solenoid114 operates valve 112 to seal off the pressurized air-source whiledeenergization of solenoid 127 permits the above mentioned restoringspring to retract plunger 126 and rotate arm 123 in a counter-clockwisedirection to seat metering pin 96 within tapered channel 81 thusterminating the flow of lacquer to nozzle 55.- It would be but a matterof simple expediency to utilize a conventional timing mechanism toinitiate, time, and terminate the above-mentioned spray Iilmingoperations in a predetermined sequence, in conjunction with drive motoroperation, to apply lacquer film layers having a high degree ofuniformity to cathode-ray tube envelopes.

ln summary, the subject invention, as embodied in the spray tilmingapparatus depicted in Figure 1, avoids the limitations of the prior artby incorporating coaxial air and lacquer conduits which are adaptable torotatable film spraying operations without the requirement of a rotatinglacquer seal, thereby obviating the necessity of coping with theinherently disagreeable qualities of lacquer material generallyencountered under such conditions. The disclosed embodiment provides fora permanent lacquer source and utilizes but a single rotating element,i. e., outer conduit 93. Furthermore in view of the fact that nozzle 55(as well as uprights 63) admits of facile interchangeability, theapplication of this novel apparatus to a variety of spray filmingoperations is enhanced. In obviating the requirement of spinning thecathode-ray tube envelope, simplified adaptation to automationfacilities is realizable since the described apparatus of Figure l canbe readily positioned upon vertically displaceable platforms to permitinsertion of nozzle S5 within a cathode-ray tube envelope. Therequirement for repositioning the envelope upon the spraying apparatus,which is inherent in apparatus taught in the prior art, is avoided; inthe application of the subject invention to automation activities, thecathode-ray tube envelope need never be disassociated from its conveyor.

While a particular embodiment of the invention has been shown anddescribed, it will be obvious to those skilled in the art that changesand modifications may be made without departing from the invention inits broader aspects, and, therefore, the aim in the appended claims isto cover all such changes and modifications as fall within the truespirit and scope of the invention.

I claim:

l. Apparatus for applying an organic lm to the exposed surface of aluminescent screen aixed to the faceplate of a cathode-ray tube envelopecomprising: means for supporting said envelope in a xed position withits axis substantially vertically oriented and said faceplate uppermost;solution conveying means comprising a stationary inner conduit and arotatable outer conduit coaxial with said inner conduit, said coaxialconduits extending vertically into said envelope from below; a liquidsupply of lacquer material coupled to said inner conduit; a supply ofcompressed gas coupled to said outer conduit; a nozzle fixed to theupper extremity of said outer conduit and communicating with both saidconduits; and means, including means for rotating said outer conduitwith respect to said inner conduit, for producing a rotating spray ofatomized lacquer material within said envelope and directed toward saidluminescent sceen.

2. Apparatus for applying an organic film to the exposed surface of aluminescent screen affixed to the faceplate of a cathode-ray tubeenvelope comprising: means for supporting said envelope in a fixedposition with its axis substantially vertically oriented and saidfaceplate uppermost; solution conveying means comprising a stationaryinner conduit and a rotatable outer conduit coaxial with said innerconduit, said coaxial conduits extending vertically into said envelopefrom below; a liquid supply of lacquer material under pressure coupledto said inner conduit; a supply of compressed gas; means including arotary air seal for supplying said gas to said outer conduit; a nozzleincluding a volatilization chamber xed to the upper extremity of saidouter conduit and communicating with both said conduits; and means,including means for rotating said outer conduit with respect to saidinner conduit, for producing a rotating spray of atomized lacquer withinsaid envelope directed toward said luminescent screen.

No references cited.

